The invention relates to a drilling device with a drilling apparatus for drilling inside a casing tube, wherein the drilling apparatus has a supporting frame with a fastening means for fixation with respect to the casing tube and a drilling tool, which is driven in a rotating manner via a telescopic rod by means of a drill drive arranged on the supporting frame.
The invention further relates to a drilling method for producing a borehole inside a casing tube, wherein a supporting frame of a drilling apparatus is fixed with respect to the casing tube and, by means of a drill drive arranged on the supporting frame, a drilling tool is driven in a rotating manner via a telescopic rod, whereby soil material is removed as drill cuttings inside the casing tube and received in the drilling tool.
A drilling device and a drilling method of such type are known from EP 1 154 078 B1. For the production of a drilled pile in soft underground a casing tube is initially pressed or twisted in by means of a known introduction device. Subsequently, to remove the soil material inside the casing tube a drilling apparatus with a supporting frame is used via a crane means. To this end the supporting frame is clamped at the upper end of the casing tube. For the drilling tool use is made of a drilling bucket which is lowered by the crane means via a telescopic Kelly rod. The drilling tool of the drilling apparatus is driven in a rotating manner via the Kelly rod by a drill drive that is arranged on the clamped supporting frame.
As soon as the receiving space of the drilling bucket is filled with removed soil material, the drilling tool is lifted again by the crane means. Afterwards, the supporting frame is detached from the casing tube and the entire drilling apparatus is swung laterally with respect to the casing tube. In this position the drilling bucket is emptied.
In order to continue the drilling process the drilling apparatus is then placed onto the casing tube again, the supporting frame is clamped thereto and the drilling apparatus is lowered once more.
On completion of the drilling process the drilling apparatus is removed in its entirety using the crane means and the cavity developed inside the casing tube can be filled for example by inserting a reinforcement cage made of steel and a concrete mass for producing a foundation pile.
All in all, this drilling method is very economical because on completion of drilling the drilling apparatus can be moved by the crane means to another casing tube so that the next drilling process can be commenced immediately afterwards. Due to the fact that the drilling apparatus can be moved in a quick and efficient way via a cable suspension on a crane means, a “flying drilling apparatus”, so to speak, is created.
In the case of unfavorable weather conditions, for example in the case of poor visibility or strong winds, the placing of the drilling apparatus onto the casing tube and the clamping of the supporting frame call for a high degree of experience and skill of the operator inside the crane means. Swaying movements of the drilling apparatus suspended on the crane cable can give rise to delays in the work process.